Plasma Etching Of Aluminum Research Articles

Nanowhiskers formation by radio frequency Ar/O 2 plasma etching of aluminum coated diamond films

Diamond nanowhiskers were fabricated by etching as-grown and aluminum coated diamond films in radio frequency (RF) Ar/O 2 plasma. It was found that diamond nanowhiskers could be obtained by anisotropic etching of both kinds of films. For the as-grown diamond film, the whiskers randomly formed on the diamond surface with higher etching rate. However, for the Al-coated diamond film, an energy dispersive X-ray spectroscopy measurement revealed that the distribution of the whiskers was the same as that of the coated Al particles. During the etching process, Al particles served as masks contributing to restraining the etching of the film underneath. It was found that the distribution of the whiskers was significantly influenced by the Al coating. The whiskers (1 μm in height and 50 nm in diameter) could be obtained under the optimum etching condition. In addition, the dependence of the distribution of the whiskers on Al coating time was demonstrated.

Study on the Properties of Interlayer Low Dielectric Polyimide during Cl-Based Plasma Etching of Aluminum

The properties of polyimide for interlayer dielectric applications are investigated during plasma etching of aluminum on it. Chlorine-based plasma generally used for aluminum etching results in an increase in the dielectric constant of polyimide, while SF6 plasma exhibits a high polyimide etch rate and a reducing effect of the dielectric constant. The leakage current of polyimide is significantly suppressed after plasma exposure. An optimal combination of Al etch with Cl2 plasma and polyimide etch with SF6 plasma is expected to be a good tool for realizing multilevel metallization structures.

Toxicological investigations in the semiconductor industry: IV. Studies on the subchronic oral toxicity and genotoxicity of vacuum pump oils contaminated by waste products from aluminum plasma etching processes.

Dry etching processes in semiconductor manufacturing use ionized gases in closed reactors at pressures below 1 torr. Vacuum pump systems that service the reaction chambers are potential sources of exposure to complex mixtures of inorganic and organic compounds. These mixtures consist of unused process gases and process by-products that condense and accumulate in the vacuum pump oils. To evaluate potential hazards of dry etch vacuum equipment, a contaminated vacuum pump oil sample from a BCl3/Cl2 etching process was analyzed. The waste oil was administered by gavage for 14 or 28 days to male and female Wistar rats. Neither death nor behavioral changes occurred after subchronic treatment or during a 14-day posttreatment period. Only slight effects on body weights, clinical chemistry, and hematology data were seen in the exposed animals, although the livers of all waste oil-exposed rats of both sexes showed remarkable hypertrophic degenerations. Genotoxicological investigations were performed through the Ames assay (Salmonella assay) and the Micronucleus assay. The contaminated oil sample caused clear genotoxic effects in both test systems.

Toxicological investigations in the semiconductor industry: III: Studies on prenatal toxicity caused by waste products from aluminum plasma etching processes.

The prenatal toxic effects of contaminated vacuum pump oil (Sample A) and solid waste products (Samples B and C) originating from aluminum plasma etching processes in semiconductor manufacturing were investigated. Three strains of pregnant mice with different degrees of sensitivity during organogenesis (days 6-15 of gestation) were treated daily with 1000 mglkg b.w. (Sample A), 500 or 750 mg/kg b.w. (Sample B), and 250, 500, or 750 mg/kg b.w. (Sample C). On day 18 of pregnancy, the animals were killed and examined for gross changes, number and weight of live fetuses, as well as the number of postimplantation losses and malformations. Analytical data showed that the investigated wastes contained various halogenated hydrocarbons and inorganic compounds. Sample A revealed no signs of prenatal toxic action. In contrast, administration of Samples B and C caused strong prenatal toxic effects. The number of live fetuses declined in a dose--related manner, and evidence of intrauterine growth retardation was noted in fetuses that survived to day 18. The number of fetuses with malformations (only cleft palates) rose significantly in accordance with the doses and sensitivity of the strains (> 95 % of the fetuses of the most sensitive strain after 750 mg/kg; 85% after 500 mg/kg).

Genotoxicity assessment of waste products of aluminum plasma etching with the SOS chromotest

We evaluated 36 characteristic waste products from the plasma etching of aluminum for genotoxicity with the SOS chromotest. The majority of the samples showed genotoxic activity in tester strain Escherichia coli PQ37 without metabolic activation using S9 mix. In the presence of S9, a deactivation of the samples was regularly observed. Comparable studies with the Salmonella/microsome (Ames) test using tester strains Salmonella typhimurium TA98 and TA100 indicated actual mutagenicity of waste products. Gas chromatograms of the organic constituents of all waste products were performed in parallel with the genotoxicity assays. In contrast to the similarity of the peak patterns of all chromatograms, the biological effects of individual waste samples showed large differences. Information on chemical composition and the SOS chromotest results of a representative sample recovered over a period of 2 years is given. For this sample, the influences of sample preparation and cytotoxic matrix effects on the test parameters are also shown.

Flow and transport modeling of a low pressure plasma etching system

Plasma etching of aluminum–copper alloys is performed at high densities and low pressures (10 mTorr) in a modified parallel plate plasma etching system with a Cl2/BCl3 gas chemistry. In this study, flow modeling is used to characterize the etching environment. The flow distribution and transport of chemical species within the reactor is modeled by the commercially available fluid dynamic software package, fluent, to predict metal etch rate and uniformity patterns on 6 in. aluminum wafers. Flow velocity vectors and chemical species distributions are presented. Cl2 is considered as the primary etchant by the single step surface reaction 3Cl2+2Al=2AlCl3. [D. Smith and R. Bruce, J. Electrochem. Soc. 129, 2045 (1982).] A good fit is achieved between the measured etch pattern and the predicted pattern. The etching is determined to be primarily transport limited, with diffusion as the dominant transport mechanism. Theoretical comparisons diffusive to convective transport in this pressure region are made.

Thin oxide charging current during plasma etching of aluminum

CV measurement is shown to be a more sensitive technique for characterizing plasma-etching induced damage than oxide breakdown. Plasma etching of Al is shown to produce severe distortions in the oxide CV characteristics, from which one can easily deduce the plasma charging current over many orders of magnitude. A clear radial variation of stressing is found and the charging current increases in proportion to the Al peripheral length rather than the area. Using the measured 10-pA/ mu m of the charging current, one should be able to predict the impact of this etch process on oxide integrity and interface stability for a given antenna geometry.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Equipment modelling of CVD and etching

Abstract This paper presents results of equipment simulation giving applications of the fluid-dynamic solution to three commonly used reactors in the semiconductor industry — Tungsten CVD, Aluminum plasma etching, and Poly LPCVD. The results obtained include the determination of three-dimensional profiles for pressure, temperature, velocity, concentration of different chemical species, etch rates, deposition rates and uniformity over the wafer. This simulation technique is an important tool for equipment and process optimization by both the equipment suppliers and process engineers, because it allows a better visualization of the variables that control the process and allows a fast estimation of how changes on the process parameters or hardware configuration influence the results.

A thermochemical model for the plasma etching of aluminum in BCl3/Cl2 and BBr3/Br2

This article describes a quantitative Recipe Map which has been constructed to target the controllable gas flows, wafer loading, and temperature settings predicted to result in the optimum BCl3/Cl2 and BBr3/Br2 plasma etching of aluminum for a given reactor and background oxygen pressure. The numerical predictions of this Recipe Map are based on modeling the plasma as a steady state flow system in which all thermodynamically predicted chemical reactions occur with collision limited kinetics, and where, in addition, physical sputtering removes material from the ion-bombarded surfaces. Anisotropic etching is caused by the sputtering of deposited oxide which allows the chemical etching of the underlying Aluminum. Although this model is very simple, its numerical predictions are in good qualitative agreement with the observed Al etching dependence on the processing parameters in both single wafer and hex etchers. In particular, the effect of wafer loading can be quantitatively evaluated using simple formulas.

Plasma Etching of Aluminum: A Comparison of Chlorinated Etchants

The plasma‐assisted etching of aluminum in chlorine containing RF glow discharges has been studied. Use of a single parallel plate reactor permitted a direct comparison of etch results between , , , and . Separation of aluminum etching into native oxide reduction and water vapor/oxygen scavenging, and metal film etching allowed the likely rate‐limiting processes in the etch cycle to be ascertained for the different etch gases. The longer initiation period observed with and compared to appeared to be due to etch gas dissociation effects. Metal etching was believed to be limited by the removal of and residues with and and by etchant generation with .

6200. Aluminum plasma etching process using vacuum systems without cold traps

Previous investigations applying the “ring masking” technique to CCD images obtained at the South African Observatory in the period 13–18 March 1986, led to the detection of CN, C2, C3 and ([OI] + NH2) jet features in the coma of comet Halley (Cosmovici et al., Nature 332, 705–709, 1988). In complement to these results we report here the detection of new features in water ion emission at 6193 Å which may be used as a tracer for the time-dependent anisotropic emission profile of the water vapour from the cometary nucleus.South Africa images, as well as Catalina Observatory data with identical filters on 20 January and 7, 8 and 24 March 1986, are utilized in order to exclude instrumental errors. Because of the narrow bandwidth of the filter (6192±44 Å) other significant molecular contaminations are considerably reduced.The observed peculiar H2O features can be explained by the stronger H2O+/dust contrast in the ion tail or by a possible mechanism of negative charging of the dust in the cometary coma.

Reaction of atomic and molecular chlorine with aluminum

In order to quantify the contributions of atomic and molecular chlorine during the plasma etching of aluminum, a discharge-flow system was used to generate chlorine atoms upstream of a parallel-plate reactor in which aluminum samples were etched with the afterglow. Molecular dissociation in excess of 70% was achieved. Dissociation was measured in the parallel-plate reactor by gas-phase titration of the chlorine atoms with NOC1 using the chemiluminescent emission resulting from atom recombination as an end point indicator. Molecules etched aluminum at least four times faster than atoms and displayed an activation energy near zero (0.02–0.04 eV/molecule) between 35 and 150 °C. Below 25 °C etching was quenched due to the inability of products and/or contaminants to desorb. The higher molecular etch rate is believed to be the result of an enhanced sticking coefficient on the chlorinated surface. Calculation of molecular sticking coefficients based on the assumption of adsorption-limited etching are in good agreement with reported values. Temperature-dependent atom recombination on the in situ electrodes prevented accurate determination of the molecule/atom etch rate ratio and masked the activation energy for atom etching.

An XPS Study of the Plasma Etching of Aluminum with CCl4

Abstract X-ray photoelectron spectroscopy (XPS) has been employed to study the plasma etching of oxidized aluminum with CCl4. The data indicate that the plasma etching of Al/Al2O3 with CCl4. produces a complex chlorocarbon polymer. Further, during the etching process, AlCl3 is imbedded in the substrate. Post-etching with CF4 to remove the imbedded material does not remove all of the AlCl3. The remaining AlCl3 can react with water to form HCl and, therefore, initiate corrosion of the aluminum. However, the water adsorption/desorption characteristics of unetched and etched Al/Al2O3 are essentially identical.

Aluminum plasma etching process using vacuum systems without cold traps

A suitable vacuum pump system used in plasma or RIE-mode dry etching of Al and Al alloys with CCl4/Cl2 enables to operate without LN2 cold traps. A Roots pump plus rotary vane pump combination, both using inert fluid lubricant, pumps and exhausts all occurring volatile products. Condensing solid AlCl3 is quantitatively removed from the backing pump sealing fluid by means of a high speed, main stream oil purification system via an Al2O3 deep bed filter. Maintenance of the pump system is limited to just changing the Al2O3 filter elements, each time after etching of 4000 4 in. wafers. No decomposition of the sealing fluid could be observed. Any fluid remaining when exchanging the filter elements can practically be recovered by centrifuging.

Pumping chlorinated gases in plasma etching

Plasma etching of aluminum, aluminum alloys, and some other materials involves the use of chlorine-based gases which are particularly corrosive to vacuum systems if precautions are not taken. Emphasizing safety concerns, we will demonstrate the proper use of cold traps, activated charcoal sorbent, and/or inert synthetic fluids to lubricate forepumps, enabling the user to deal with this corrosion problem. The sorption capacity of activated charcoal is discussed for the proper design of sorption traps, and methods of regenerating large cold traps saturated with hazardous products are examined. Information on the use of turbomolecular pumps in reactive ion etching is also given.

Optical end-point detection for the plasma etching of aluminum : B. J. Curtis. Solid-St. Technol. 129 (April 1980)

Optical end-point detection for the plasma etching of aluminum : B. J. Curtis. Solid-St. Technol. 129 (April 1980)

Negative Electron Resists for Direct Device Lithography: II . Poly(Glycidyl Methacrylate‐Co‐3‐Chlorostyrene)—Lithographic Performance

Poly (glycidyl methacrylate‐co‐3‐chlorostyrene) (GMC) has been identified as a potential candidate for an electron resist to be used in direct device fabrication. It was previously reported (Part I) to have improved resolution and dry etching resistance over COP. This paper reports the results of an extensive evaluation of GMC. It was found to have a contrast of ∼1.6 and a sensitivity of 3 μC cm−2 at 20 kV. It was found to exhibit 1.0–1.5 μm resolution with 0.6 μm films. The resist has good adhesion for wet chemical etching of thermal and aluminum. Both the alkaline and the tri‐acid aluminum etchants, are compatible with GMC. In plasma etching, the resist etches by at least a factor of 5 slower than , polysilicon, and 8% p‐glass. In anisotropic aluminum plasma etching, GMC etches at about the same rate as aluminum, but the etch rate of the former can be markedly reduced by ion implantation prior to etching.